Minimum Altitudes for Former Periglacial Landforms Adjacent to Longitude 106°W in Colorado and New Mexico, USA, Between Latitudes 33°N and 40°N

Abstract

Minimum altitudes at which specific landforms and deposits of periglacial origin exist in Colorado and New Mexico adjacent to longitude 106° are reported on the basis of field evidence. These data were plotted in relation to altitude and latitude. Specific landforms occur in a constant relationship. Cirques always occur at higher altitude than narrow, elongate hollows and transverse solifluction lobes occur above longitudinal lobes. Periglacial forms extend 500 to 750 m below the active tundra zone, well into the forest zone. Some glacial moraines have also been modified by periglacial action. No latitudinal gradient could be identified. A comparable plot using literature sources confirms the field results.